It is mid-November in St Petersburg. A stubborn Siberian wind is freezing every molecule of moisture in the city. Inside though, where the cream of high society has gathered, the enemy is not the weather, but that French thug, Napoleon, and his marauding army drawing ever closer to Mother Russia. For this is the set of a lavish adaptation of the Tolstoy classic War and Peace, where cast and crew are in the final stretch of a 20-week production.

The rigours of the shoot seem to weigh on some of the actors. Their shoulders collapse underneath 19th-century ballroom gowns and the men scratch at their ample sideburns. The Romanian-born director Robert Dornhelm barks out instructions in English to the scene's principal actors, Ken Duken from Germany and Harry Potter star Clémence Poésy from France. It is a crucial point in the production. Duken's character, the scheming Anatole Kuragin, is hatching his plot to seduce the pure, naive Natasha. "OK, everyone. Action!" the director shouts. For good measure, a command for silence is repeated in Italian, Russian, Spanish and French. Between takes, the polyglot set resembles more an EU-Russia summit on culture than a big-budget film production.

At €28m, War and Peace is considered to be the most expensive TV mini-series ever produced in Europe - the budget is believed to be twice the usual going price. Shot in English, it involves seven countries, with actors from 10. It is the first time Russia has allowed a foreign production - led by the Italian firm Lux Vide, plus France's Pampa Production and Germany's Eos Film - of this size to shoot on Tolstoy's home turf.

Italy has put up nearly 50% of the budget, with the French and Germans throwing in substantial chunks. The remainder was funded by Spain's Grupo Interconomia and Poland's Grupo Filmowa and Polsat

Sergey Shumakov, the deputy general of TV Channel Russia (formerly called RTR), observes the commotion on set like a proud grandfather. "This is the biggest and most important television project of the century," he says, through an interpreter. It is clear he is not just speaking for his Russian audience. Tolstoy's novel, he continues, "gives the possibility for all Europeans to speak the same language. It's a way for us to show we all have the same values, and that we all feel part of Europe."

Shumakov sees big potential in further cinematic coproductions of this size with his European neighbours. He envisages Tolstoy's Anna Karenina as a possible co-production candidate. And he says that there is promise in Dostoevsky's The Possessed, but acknowledges its subject of home-grown terrorism, even in 19th-century Russia, may put off some TV network programmers around the continent. In a spirit of cooperation, Shumakov says the Russians are willing to make creative concessions as they did with War and Peace, opting, for example, to set the movie in one city, St Petersburg, not St Petersburg and Moscow as Tolstoy conceived, and condensing the original narrative's 10-year plot into four. Shumakov, through his translator, speaks with the trademark anything-is-possible confidence of a TV network head.

His partners, the ones financing the production, use more pragmatic language. Their hesitancy has little to do with Russia's reputation as a country of few media freedoms or on the political relations between Moscow and other European capitals. TV is business, they consistently say, a business that does not necessarily reward risk-takers. TV ratings are down everywhere. Programme directors want to hear about reliable ratings-grabbers, not multicultural, cross-border projects. Russia may be the exciting new frontier in TV, but will the series work back home in Milan or Milton Keynes? And, more importantly, will today's viewers be able to sit through four nights of Tolstoy in prime time when they only managed to get half-way through the book in their teens?

"Everyone is looking for two-day stories these days," Jan Mojto, Eos Film's president and one of the primary funders, says after the day's shooting is in the can. "Four nights makes it more difficult in principle. You have to convince programme controllers that they will win on four evenings. That is difficult."

There are elements to War and Peace that make for good TV, the producers insist. But, as is often the case with multi-national coproductions, not all the producers can agree on which elements to play up. For example, Italian viewers want more romance and less war. German viewers prefer more war and less romance. The compromise? In Italy, the film will run for 400 minutes; the Germans will air their version for 360 minutes. Does this mean Italians will get 40 minutes more love than the Germans? No, replies Dornhelm, the director. It is possible to accommodate national tastes, he says, even if it means films of dramatically varying lengths. The main message will not be diluted. "We will focus on the question, 'Why do men go to war'"? Over nearly a two-year period, the script went through a series of revisions, says Nicolas Traube, manager of the Paris-based production company Pampa. The early quibbles, as always, were over casting. Some countries wanted a full-figured actress to play Natasha and a more action hero-type actor to play her love interest, Pierre. Ultimately, they agreed on France's Poesy and Germany's Alexander Beyer, who resemble in demeanour and physical appearance the original Tolstoy characters. The fact that the cast consists primarily of young up-and-comers from across Europe, with just a few established actors such as Malcolm McDowell and Brenda Blethyn, is a concern to some broadcasters, the producers acknowledge.

One of the most important characters, according to Traube, is Russia itself. "To have the genuine support of Russia means we are not doing a soapy version of War and Peace," he says. The 1956 version, starring Audrey Hepburn as Natasha and Henry Fonda as Pierre, was an unapologetic Hollywood production, he recalls, adding "the plot may have been Tolstoy, but the soul certainly was not". The movie a decade later by acclaimed Soviet director Sergei Bondarchuk is considered the authentic cinematic version; it won an Oscar for Best Foreign Language Film in 1969.

Still, with €28m riding on putting Tolstoy in prime time, the producers are more concerned with ratings than critical response. Shooting finished last week in the Lithuanian capital, Vilnius - the other principal location - and the focus is now on post-production and pitching the film to broadcasters in Britain, America and Australia. This is the job of Lux Vide, which conceived the idea and put up the bulk of the money along with Rai Fiction, a production unit of the Italian state broadcaster. Well known for its Bible series dramas, Lux is confident its multinational remake will sell abroad. The film will air next summer or early autumn in Italy, France, Germany, Austria, Spain, Poland, Russia and Lithuania, the countries that have signed on to the coproduction.

Whether or not there will be future co-productions with the Russians remains to be seen. However, both sides say they are genuinely interested in working together again, even if the Russians are bringing very little money, if any, to the project. "What they bring is credibility," Traube says.

Whether Russian credibility will matter much in Milton Keynes is anybody's guess.